Method for securing valve seat parts in internal combustion engines and like machines



June 1934- G w. SMITH. JR 1,9

HETHOD FOR SECURING VALVE SEAT PARTS IN INTERNAL COMBUSTION ENGINES AND LIKE MACHINES Filed July 24. 1931 Fijf ' 1v VENTOR A rromvi 1' PATENT OFFICE METHOD Fon SECURING VALVE SEAT PARTS IN INTERNAL COMBUSTION EN ,GINES AND LIKE MACHINES George William Smith, Jr., Cleveland, Ohio, usignor to The White Motor Company, Cleveland, Ohio, a corporation of Ohio Application July 24, 1931, Serial N6. 552,868

Claims.

This invention relates to internal combustion engines, and to like machines in which the valve seats are heated to varying temperatures.

It is often desirable in the construction of 5 machines of the type to which this invention pertains, in order to obtain, certain qualities in the valve seats, to construct the valve seats of a different material having a greater coeflicient of. thermal expansion than that employed in theassociated parts of the machines. In those instances in which the valve seat material has a substantially different coefficient of thermal expansion than that oi the material ofthe associated parts of the machines, difficulty is encountered in securing the valve seats in place due to the large diflference in expansion of the valve seats and the parts to which they are attached. It is an object of this invention to provide an improved method for efiecting the securement y within internal combustion engines, and like machines, of valve seat parts having difierent thermal expansions than theassociated parts of the machines.

In the drawing: Figure 1 is-a, fragmentary side elevation, partly in section, of anengine equipped with valve seat parts secured in place in accordance with this invention, the plane of the portion in section being indicated in Figure 2 by the line 1--1.

' Figure 2 is a fragmentary bottom plan view of the cylinder head of the engine illustrated in Figure 1.

Figure 3 is an enlarged sectional view of th cylinder head, and of a protector member employed within the recessed seats at the end of the exhaust passages during a hereafter described brazing process.

Figure dis a perspective view, drawn to a relatively large. scale, of a valve seat part of the type illustrated in Figures 1 and 2.

Figure 5 is a perspective view, drawn to the same scale as Figure 4, of a member of the same type as those meunted with the valve seat parts illustrated in Figures. 1 and 2, and

Figure 6 is an enlarged sectional view of aportion of the cylinderhead, the section being taken through an exhaust port.

Referring to the drawing, the engine therein illustrated-consists in general of I a conventional assembly-of conventional parts including a cylinder'block 10 and a cylinder head 11. The cylinderhead 11 is constructed of cast iron and is formed with inlet andexhaust passages 12 and 13 controlled respectively by inlet and exhaust valves 14 and 15. The cylinder head is further formed with recessed seats 16 surrounding the interior ends of the exhaust passages 13, and

mounted within each of the seats 16 there is an aluminum bronze valve seat part 17 and an associated annular steel part 18 which are brazed together and to the walls of the seat.

The aluminum bronze alloy used in the construction of the valve seat parts 1'? is particularly adapted for use in the valve seats of internal combustion engines, but due to its relatively high coefficient of thermal expansion is exceedingly difiicult to secure in place in a cast iron part of an engine in the form of an insert.-

The difiiculty met with in securing an aluminum bronze insert in a cast iron part of an engine by means of brazing, or like process, is the difiiculty encountered in procuring a bond between the parts of sufl'icient strength to withstand the ef forts of the aluminum bronze part to expand and contract a greater amount than its seat in the cast iron part.

In the present construction, wherein the aluminum bronze parts are bonded to inner steel parts having smaller thermal expansions, a portion oi' the stress set up by the aluminum bronze parts in their efforts to expand and contract a greateramount'than their seats in the cylinder head is borne by the bonds intermediate the aluminum bronze parts and the steel parts. As

a result, both the bonds connecting the aluminum bronze parts to their seats, and the bonds con necting such parts to the steel parts, are subiected to less stress than would be imposed upon the bonds between the inserts and seats of a similar' construction in which the steel parts were omitted,

' Prior to securing the steel parts 18 and the valve seat parts 1'7 within the cylinder head, the steel parts are brazed within the valve seat parts. In carrying out this brazing process, the aluminum bronze parts and the steel parts are placed within the flame of a gas torch and heated to a temperature of about 1450 degrees Fahrenheit, the flame being adjusted at the termination of the heating period so as to maintain the parts at such. temperature. The surfaces of the aluminum bronze. parts and the steel parts are then coated with a flux of Iused borax which is spread over the surface of the parts in any suitable manner after being reduced to amolten state by the heat of the flame; following which, the steel parts are coated with a silver solder consisting of approximately 45 per cent silver, '25 per cent zinc, and- 30 per cent copper, the solder like the flux being applied in a molten state after being melted by the flame. The steel parts are then placed within the aluminum bronze parts and the annular spaces between the parts filled with molten silver solder of the same character as that previously described, the solder as before being reduced to a molten state by the heat of the flame.

The units formed by the process just described, consisting of the aluminum bronze part 17 and the associated steel parts 18, are secured within the cylinder head by a brazing process similar to that disclosed in applicants Patent #1,838,160. In carrying out this process the cylinder head is first preheated to a sufiiciently high temperature to prevent rupture by the spot heating employed in later operations. The preheating of the cylinder head is accomplished in a furnace of the two chamber type wherein the head is both heated uniformly and protected from the corrosive action of the flames or like agents.

Following the preheating. of the cylinder head, it is placed within a suitable heat retaining container located under a slidably and an adjustably mounted gas torch, and the top of the con-' tainer covered with asbestos sheets except for a small portion overlying one of the exhaust ports. A metal protector ring 19 is then inserted into the seat not covered by the asbestos sheets, and a protector member (not shown) placed within the subjacent valve guide, after which the torch is lighted and arranged so that its fiame impinges upon the protector ring and the adjacent portion 'of the cylinder head. The flame is allowed to heat the protector ring, the associated seat, and the surrounding portion of the cylinder head to a temperature of about 1450 degrees Fahrenheit, a temperature slightly above the melting point of the solder employed in later operations, and then adjusted to maintain the protector ring and the seat at such temperature. The walls of the uncovered seat are then coated with a flux of fused borax which is applied through apertures 20 in the protector ring by means of a suitable tool after being reduced to a molten state by the heat of the flame, the protector ringbeing rotated during the operation so as to spread the flux over the entire surface of the walls of the seat.

Following the application of the borax flux to the walls of the seat, the walls of the seat are coated with a hard solder of the same composition as that employed in brazing the steel part within the aluminum bronze part. The solder is applied in the form of a slender bar which is inserted into the difierent apertures 20 in the protector ring. and used as a means for rotating the protector ring to distribute over 'the surface of the walls of the seat the molten solder melted from its lower end. After the walls of the seat have been coated with solder, the protector ring is removed, and a unit, consisting of an aluminum bronze part and associated steel part, inserted.

.As soon as the valve seat part and the steel part have obtained the temperature of the seat,

the space between the valve seat part and the walls of the seat is filled with hard solder of the same character as that previously described, the solder being melted from the ends of bars inserted into notches 21 formed in the outer periphery of the aluminum bronze part, and the aluminum bronze part being rotated during the operation so as to insure that the entire space is filled. I

After the space between the aluminum bronze part and the walls of the seat have been filled with solder, the apparatus is arranged for brazing a second valve seat unit within the cylinder head.

The protector member is removed from the valve guide, and the cover for the container adjusted so as to cover the portion of the cylinder head then subjected to the heat of the flame and to uncover a second seat. The protector ring 19 is then inserted into the seat uncovered by the foregoing adjustment of the cover, and the other protector member placed within the subjacent valve guide; after which, the torch is adjusted so that its flame impinges upon the protector ring 19 and the surrounding portion of the cylinder head. A second unit consisting of an aluminum bronze part and an inner steel part is then brazed with in the cylinder head in the seat previously uncovered by adjustment of 'the cover for the container, the procedure employed being the same as that employed in brazing the first unit in place. When units each consisting of an aluminum bronze valve seat part and an inner steel part have been brazed into the seat in the cylinder head, the flame is extinguished and the head allowed to cool; following which the excess brazing material is removed and the seating surfaces 22 added.

The inlet Valves 14 are provided with seats 23 formed in the cast iron cylinder head 11, but if desired may be provided with aluminum bronze valve seat parts secured in place in a similar manner to the valve seat parts 17. Such construction is, however, not warranted in the. present engine as seats for the inlet valves are not subjected to sufiiciently high temperatures as to materially lessen their resistance to wear, or to cause a material amount of scaling or pitting of such parts.

Although the foregoing description has been concerned with the securing of an aluminum bronze valve seat part in a cast iron part, it is to be understood that my invention is of a more general nature, and may be employed to secure valve seats of various materials to parts of various materials.

It is to be further understood that my invention oomprehendsthe use in any particular installation of an inner part of any material consonant with the function of such part.

It is to be further understood that my invention is not limited to the herein described brazing processes, but is broad enough to comprehend any method, or combination of methods for securing the parts together, in which the connections realized between the parts are capable of withstanding the stresses imposed thereon.

What I claim is:

1. The method for effecting the securement 130 within an internal combustion engine or like machine of a valve seat part having a different thermal expansion than the part to which it is to be affixed, which consists in bonding said valve seat part within a seat formed 'in said second named 135 part, and to a third part located within said valve seat part and having a thermal expansion similar to that of said second named part.

2. The method for effecting the securement within an internal combustion engine or like machine of a valve seat part having a larger thermal expansion than the part to which it is to be affixed, which consists in bonding said valve seat part to said second named part, and to a third part located within and having a smaller thermal expansion than said valve seat part.

3. The method for eifecting the securement within an internal combustion engine or like machine of a valve seat part having a larger thermal expansion than the part to which it is to be af- 150 fixed, which consists in brazing within said valve seat part an inner part having a smaller thermal expansion than said valve seat part, forming within said second named part a seat for the unit consisting of said valve seat part and said inner part, and brazing said unit within the seat formed in said second named part.

4. The method for effecting the securement within an internal combustion engine or like machine of an annular valve seat part having a different thermal expansion than the part to which it is to be aifixed, which consists in securing said valve seat part within a seat formed in said second-named part by means of a fused metallic bond, and securing within said valve seat part an annular member having a thermal expansion similar to that of said second named part by means of a fused metallic bond.

5. The method for efiecting the securement within an internal combustion engine or like machine of an annular valve seat part having a larger thermal expansion than the part to which it is to be affixed, which consists in securing said valve seat part within a seat formed in said second named part by means of a fused metallic bond, and securing within said valve seat part an annular member having a smaller thermal expansion than said valve seat part by means of a fused metallic bond.

GEORGE WILLIAM SMITH, JR. 

